As this type of lamp, a headlamp is known in which a reflector which reflects light emitted from a light source is displaced by an actuator and the direction of the reflected light is changed by an optical system provided in the lamp. The light emitted from the light source and reflected by the reflector illuminates a predetermined area ahead of the vehicle. The illumination light scans within a scanning area which has a wider area than the predetermined area as a result of the actuator displacing the reflector periodically. The scanning is executed at a higher frequency than a frequency at which human eyes can recognize the turning on and off of light shone, whereby it appears to the eyes of occupants in the vehicle that the whole of the scanning area is illuminated (for example, refer to International Unexamined Patent Application Publication No. 2011/129105, Japanese Patent Publication No. 4881255, Japanese Patent Publication No. 5118564).